Electronic circuitry is often powered by electricity received from line currents. To condition the incoming line current to one or more desired voltages at which circuitry operates, oftentimes a voltage regulator is present. Although many different types of voltage regulation circuits exist, a common regulator found in electronic equipment is a switched mode power supply (SMPS). Such a power supply receives an incoming voltage, i.e., an unregulated voltage at a first voltage level and converts the voltage to one or more desired voltage levels, which may be higher or lower than the input voltage level. The SMPS further regulates the output voltage level to reduce the effects of spikes or surges on the line.
Switched mode power supplies typically include a switching transistor that is switched on and off by a drive signal, e.g., it is controlled in a pulse width modulated (PWM) manner. When the switching transistor is on, a voltage is provided to charge an inductive mechanism in the power supply such as one or more inductors or coils of a transformer. When the drive signal is switched off, the inductive mechanism discharges to provide the desired voltage.
While such switched mode power supplies are suitable for many applications, their application becomes difficult when a load that is coupled to the power supply requires widely differing power levels in different modes of operation. To provide the desired multiple voltages, various mechanisms are used, including the presence of multiple inductors that are switched into or out of the power supply based upon the required load. However, the presence of multiple inductors increases the size of the power supply. Furthermore, switching of the multiple inductors increases complexity. Alternately, external control may be provided to change a switching frequency (i.e., duty cycle) of the switched mode power supply based on changes in the operation mode of the load. However this also presents complexities. A need thus exists for improved regulation of power to a load.